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<a class="jxr_linenumber" name="1" href="#1">1</a>   <em class="jxr_comment">/*</em>
<a class="jxr_linenumber" name="2" href="#2">2</a>   <em class="jxr_comment"> * Licensed to the Apache Software Foundation (ASF) under one or more</em>
<a class="jxr_linenumber" name="3" href="#3">3</a>   <em class="jxr_comment"> * contributor license agreements.  See the NOTICE file distributed with</em>
<a class="jxr_linenumber" name="4" href="#4">4</a>   <em class="jxr_comment"> * this work for additional information regarding copyright ownership.</em>
<a class="jxr_linenumber" name="5" href="#5">5</a>   <em class="jxr_comment"> * The ASF licenses this file to You under the Apache License, Version 2.0</em>
<a class="jxr_linenumber" name="6" href="#6">6</a>   <em class="jxr_comment"> * (the "License"); you may not use this file except in compliance with</em>
<a class="jxr_linenumber" name="7" href="#7">7</a>   <em class="jxr_comment"> * the License.  You may obtain a copy of the License at</em>
<a class="jxr_linenumber" name="8" href="#8">8</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="9" href="#9">9</a>   <em class="jxr_comment"> *     <a href="http://www.apache.org/licenses/LICENSE-2.0" target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.0</a></em>
<a class="jxr_linenumber" name="10" href="#10">10</a>  <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="11" href="#11">11</a>  <em class="jxr_comment"> * Unless required by applicable law or agreed to in writing, software</em>
<a class="jxr_linenumber" name="12" href="#12">12</a>  <em class="jxr_comment"> * distributed under the License is distributed on an "AS IS" BASIS,</em>
<a class="jxr_linenumber" name="13" href="#13">13</a>  <em class="jxr_comment"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</em>
<a class="jxr_linenumber" name="14" href="#14">14</a>  <em class="jxr_comment"> * See the License for the specific language governing permissions and</em>
<a class="jxr_linenumber" name="15" href="#15">15</a>  <em class="jxr_comment"> * limitations under the License.</em>
<a class="jxr_linenumber" name="16" href="#16">16</a>  <em class="jxr_comment"> */</em>
<a class="jxr_linenumber" name="17" href="#17">17</a>  <strong class="jxr_keyword">package</strong> org.apache.commons.configuration.tree;
<a class="jxr_linenumber" name="18" href="#18">18</a>  
<a class="jxr_linenumber" name="19" href="#19">19</a>  <strong class="jxr_keyword">import</strong> java.util.List;
<a class="jxr_linenumber" name="20" href="#20">20</a>  
<a class="jxr_linenumber" name="21" href="#21">21</a>  <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="22" href="#22">22</a>  <em class="jxr_javadoccomment"> * &lt;p&gt;</em>
<a class="jxr_linenumber" name="23" href="#23">23</a>  <em class="jxr_javadoccomment"> * Definition of an interface for evaluating keys for hierarchical</em>
<a class="jxr_linenumber" name="24" href="#24">24</a>  <em class="jxr_javadoccomment"> * configurations.</em>
<a class="jxr_linenumber" name="25" href="#25">25</a>  <em class="jxr_javadoccomment"> * &lt;/p&gt;</em>
<a class="jxr_linenumber" name="26" href="#26">26</a>  <em class="jxr_javadoccomment"> * &lt;p&gt;</em>
<a class="jxr_linenumber" name="27" href="#27">27</a>  <em class="jxr_javadoccomment"> * An &lt;em&gt;expression engine&lt;/em&gt; knows how to map a key for a configuration's</em>
<a class="jxr_linenumber" name="28" href="#28">28</a>  <em class="jxr_javadoccomment"> * property to a single or a set of configuration nodes. Thus it defines the way</em>
<a class="jxr_linenumber" name="29" href="#29">29</a>  <em class="jxr_javadoccomment"> * how properties are addressed in this configuration. Methods of a</em>
<a class="jxr_linenumber" name="30" href="#30">30</a>  <em class="jxr_javadoccomment"> * configuration that have to handle property key (e.g.</em>
<a class="jxr_linenumber" name="31" href="#31">31</a>  <em class="jxr_javadoccomment"> * {@code getProperty()} or {@code addProperty()} do not interpret</em>
<a class="jxr_linenumber" name="32" href="#32">32</a>  <em class="jxr_javadoccomment"> * the passed in keys on their own, but delegate this task to an associated</em>
<a class="jxr_linenumber" name="33" href="#33">33</a>  <em class="jxr_javadoccomment"> * expression engine. This expression engine will then find out, which</em>
<a class="jxr_linenumber" name="34" href="#34">34</a>  <em class="jxr_javadoccomment"> * configuration nodes are addressed by the key.</em>
<a class="jxr_linenumber" name="35" href="#35">35</a>  <em class="jxr_javadoccomment"> * &lt;/p&gt;</em>
<a class="jxr_linenumber" name="36" href="#36">36</a>  <em class="jxr_javadoccomment"> * &lt;p&gt;</em>
<a class="jxr_linenumber" name="37" href="#37">37</a>  <em class="jxr_javadoccomment"> * Separating the task of evaluating property keys from the configuration object</em>
<a class="jxr_linenumber" name="38" href="#38">38</a>  <em class="jxr_javadoccomment"> * has the advantage that many different expression languages (i.e. ways for</em>
<a class="jxr_linenumber" name="39" href="#39">39</a>  <em class="jxr_javadoccomment"> * querying or setting properties) can be supported. Just set a suitable</em>
<a class="jxr_linenumber" name="40" href="#40">40</a>  <em class="jxr_javadoccomment"> * implementation of this interface as the configuration's expression engine,</em>
<a class="jxr_linenumber" name="41" href="#41">41</a>  <em class="jxr_javadoccomment"> * and you can use the syntax provided by this implementation.</em>
<a class="jxr_linenumber" name="42" href="#42">42</a>  <em class="jxr_javadoccomment"> * &lt;/p&gt;</em>
<a class="jxr_linenumber" name="43" href="#43">43</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="44" href="#44">44</a>  <em class="jxr_javadoccomment"> * @since 1.3</em>
<a class="jxr_linenumber" name="45" href="#45">45</a>  <em class="jxr_javadoccomment"> * @author &lt;a</em>
<a class="jxr_linenumber" name="46" href="#46">46</a>  <em class="jxr_javadoccomment"> * href="<a href="http://commons.apache.org/configuration/team-list.html" target="alexandria_uri">http://commons.apache.org/configuration/team-list.html</a>"&gt;Commons</em>
<a class="jxr_linenumber" name="47" href="#47">47</a>  <em class="jxr_javadoccomment"> * Configuration team&lt;/a&gt;</em>
<a class="jxr_linenumber" name="48" href="#48">48</a>  <em class="jxr_javadoccomment"> * @version $Id: ExpressionEngine.java 1206474 2011-11-26 16:14:09Z oheger $</em>
<a class="jxr_linenumber" name="49" href="#49">49</a>  <em class="jxr_javadoccomment"> */</em>
<a class="jxr_linenumber" name="50" href="#50">50</a>  <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">interface</strong> <a href="../../../../../org/apache/commons/configuration/tree/ExpressionEngine.html">ExpressionEngine</a>
<a class="jxr_linenumber" name="51" href="#51">51</a>  {
<a class="jxr_linenumber" name="52" href="#52">52</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="53" href="#53">53</a>  <em class="jxr_javadoccomment">     * Finds the node(s) that is (are) matched by the specified key. This is the</em>
<a class="jxr_linenumber" name="54" href="#54">54</a>  <em class="jxr_javadoccomment">     * main method for interpreting property keys. An implementation must</em>
<a class="jxr_linenumber" name="55" href="#55">55</a>  <em class="jxr_javadoccomment">     * traverse the given root node and its children to find all nodes that are</em>
<a class="jxr_linenumber" name="56" href="#56">56</a>  <em class="jxr_javadoccomment">     * matched by the given key. If the key is not correct in the syntax</em>
<a class="jxr_linenumber" name="57" href="#57">57</a>  <em class="jxr_javadoccomment">     * provided by that implementation, it is free to throw a (runtime)</em>
<a class="jxr_linenumber" name="58" href="#58">58</a>  <em class="jxr_javadoccomment">     * exception indicating this error condition.</em>
<a class="jxr_linenumber" name="59" href="#59">59</a>  <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="60" href="#60">60</a>  <em class="jxr_javadoccomment">     * @param root the root node of a hierarchy of configuration nodes</em>
<a class="jxr_linenumber" name="61" href="#61">61</a>  <em class="jxr_javadoccomment">     * @param key the key to be evaluated</em>
<a class="jxr_linenumber" name="62" href="#62">62</a>  <em class="jxr_javadoccomment">     * @return a list with the nodes that are matched by the key (should never</em>
<a class="jxr_linenumber" name="63" href="#63">63</a>  <em class="jxr_javadoccomment">     * be &lt;b&gt;null&lt;/b&gt;)</em>
<a class="jxr_linenumber" name="64" href="#64">64</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="65" href="#65">65</a>      List&lt;ConfigurationNode&gt; query(<a href="../../../../../org/apache/commons/configuration/tree/ConfigurationNode.html">ConfigurationNode</a> root, String key);
<a class="jxr_linenumber" name="66" href="#66">66</a>  
<a class="jxr_linenumber" name="67" href="#67">67</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="68" href="#68">68</a>  <em class="jxr_javadoccomment">     * Returns the key for the specified node in the expression language</em>
<a class="jxr_linenumber" name="69" href="#69">69</a>  <em class="jxr_javadoccomment">     * supported by an implementation. This method is called whenever a property</em>
<a class="jxr_linenumber" name="70" href="#70">70</a>  <em class="jxr_javadoccomment">     * key for a node has to be constructed, e.g. by the</em>
<a class="jxr_linenumber" name="71" href="#71">71</a>  <em class="jxr_javadoccomment">     * {@link org.apache.commons.configuration.Configuration#getKeys() getKeys()}</em>
<a class="jxr_linenumber" name="72" href="#72">72</a>  <em class="jxr_javadoccomment">     * method.</em>
<a class="jxr_linenumber" name="73" href="#73">73</a>  <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="74" href="#74">74</a>  <em class="jxr_javadoccomment">     * @param node the node, for which the key must be constructed</em>
<a class="jxr_linenumber" name="75" href="#75">75</a>  <em class="jxr_javadoccomment">     * @param parentKey the key of this node's parent (can be &lt;b&gt;null&lt;/b&gt; for</em>
<a class="jxr_linenumber" name="76" href="#76">76</a>  <em class="jxr_javadoccomment">     * the root node)</em>
<a class="jxr_linenumber" name="77" href="#77">77</a>  <em class="jxr_javadoccomment">     * @return this node's key</em>
<a class="jxr_linenumber" name="78" href="#78">78</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="79" href="#79">79</a>      String nodeKey(<a href="../../../../../org/apache/commons/configuration/tree/ConfigurationNode.html">ConfigurationNode</a> node, String parentKey);
<a class="jxr_linenumber" name="80" href="#80">80</a>  
<a class="jxr_linenumber" name="81" href="#81">81</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="82" href="#82">82</a>  <em class="jxr_javadoccomment">     * Returns information needed for an add operation. This method gets called</em>
<a class="jxr_linenumber" name="83" href="#83">83</a>  <em class="jxr_javadoccomment">     * when new properties are to be added to a configuration. An implementation</em>
<a class="jxr_linenumber" name="84" href="#84">84</a>  <em class="jxr_javadoccomment">     * has to interpret the specified key, find the parent node for the new</em>
<a class="jxr_linenumber" name="85" href="#85">85</a>  <em class="jxr_javadoccomment">     * elements, and provide all information about new nodes to be added.</em>
<a class="jxr_linenumber" name="86" href="#86">86</a>  <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="87" href="#87">87</a>  <em class="jxr_javadoccomment">     * @param root the root node</em>
<a class="jxr_linenumber" name="88" href="#88">88</a>  <em class="jxr_javadoccomment">     * @param key the key for the new property</em>
<a class="jxr_linenumber" name="89" href="#89">89</a>  <em class="jxr_javadoccomment">     * @return an object with all information needed for the add operation</em>
<a class="jxr_linenumber" name="90" href="#90">90</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="91" href="#91">91</a>      <a href="../../../../../org/apache/commons/configuration/tree/NodeAddData.html">NodeAddData</a> prepareAdd(<a href="../../../../../org/apache/commons/configuration/tree/ConfigurationNode.html">ConfigurationNode</a> root, String key);
<a class="jxr_linenumber" name="92" href="#92">92</a>  }
</pre>
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